Firefox now always stores the old session, and you can access it by going to the History menu and selecting "Restore Previous Session" If you want Firefox to display the message to save the session, it can be turned back on by changing some preferences. # Type '''about:config''' into the location bar and press enter # Accept the warning message that appears, you will be taken to a list of preferences # Locate the preference '''browser.tabs.warnOnClose''', if its value is set to '''false''', double-click on it to change its value to '''true''' # Repeat this for these 3 preferences '''browser.warnOnQuit''', '''browser.warnOnRestart''' and '''browser.showQuitWarning''' ------ If you always open the last set of tabs, an alternative approach is this: # Click the orange Firefox button, then select options to open the options window # Go to the General panel # Change the setting "When Firefox starts" to "Show my windows and tabs from last time"